Club root (Plasmodiophora brassicae)

Symptoms

• Roots develop clubs (swellings) that can be 12-15 cm wide.
• The largest clubs are usually on the larger roots just below the soil surface.
• Affected seedlings do not show any root swellings until about 3 weeks after infection.
• Infection in the nursery stage results in the death of seedlings.
• When plants are attacked at a later stage, the disease rarely kills the plant, but the capacity of the affected roots to absorb minerals and water gets reduced.
• Plants wilt in hot weather but partly recover at night.
• Finally leaves become stunted, yellowish and prematurely bolt in hot weather.
• Cool, wet and acidic soils favor the development and spread of the disease.

Management

• Use only uninfected seedbeds and clean equipment.
• Soil solarization has also been found effective in reducing the inoculum.
• Use resistant cultivars if available.
• Long crop rotations with non-cruciferous crops for 6 years or longer help prevent a pathogen buildup and reduce disease incidence.
• When susceptible varieties are grown in acidic soils, finely ground limestone is thoroughly mixed into the soil six weeks before planting to raise the soil pH above 7.0.
• Lime inhibits disease development, but will not prevent a disease outbreak if the spore load in the soil is sufficiently high.
• Destruction of diseased debris and wild hosts from in and around the field helps in reduction of primary inoculum.
• Bio control agents like Pseudomonas fluorescens and Streptomyces graminofaciens helps in reducing size and growth of club as well as root infection

Chemical Control

Extremely Toxic

Highly Toxic

Moderately Toxic

Slightly Toxic